Help with identifying Hardie valve

Hi, I'm trying to figure out what 1" Hardie valve I have so I can buy a replacement diaphragm. I've looked at the various sprinkler supply stores, and I haven't found a diagram that matches -- especially with the protrusion underneath the valve.

It appears that the solenoid has been replaced at least once already, since that has the Orbit brand on it. I'm reticent to cut out the valve and replace it since I have very little room on the upstream side to work with, and digging those valves out of the dirt around them has been quite a chore. As you can see, I had to pull the valve box out of the ground to be able get at the valve at all. I'd also be happy to hear any suggestions for how to put a box back more intelligently -- whoever did the drip upgrade looks to have just cut a hole in the side of it.

mrfixit: I've seen that I can purchase both the bonnet and diaphragm -- is that what constitutes a retrofit?

I've contacted a couple of pros to see what it will cost to have them replace the valve. I think I could do it myself, but after buying the tools, I'm probably about even once you factor in time and quality of workmanship from me.

One important point is that some old valves are subject to internal cracks in the valve body itself, and the entire valve needs replaced. So if you have a leaking valve that just won't shut off 100%, replacement might be the only choice.